In science laboratories there is a growing need to operate on and store increasingly large numbers of samples. These samples need to be retrieved quickly and unambiguously as and when required. Furthermore, an increasing number of laboratories are moving to robotic handling of samples.
A typical example of this type of problem is when samples are kept in so-called cluster tubes stored in a cluster plate. Ideal for sample storage, a 1.2 ml micro-tube cluster plate comprises 96 individual 1.2 ml tubes held in place by a heavy duty rack in a standard microplate format. Made from polypropylene, each tube is fully supported at the base or around a collar to withstand the pressure applied by robotic systems. Caps or mats are provided to seal each tube individually and the lid of the cluster plate has bevelled comers for a “one way” fit. Packs of loose tubes are available in order that the rack system can be re-used. The individual positions within a plate are designated in the typical 96 well formal using letters A to H and numbers 1 to 12. Thus position F9 indicates a specific tube within the array. However, identification of a specific tube is more complicated when there are many tens of thousands of micro tube cluster plates held in the same storage area.
The concept of uniquely labelling each tube is known. For example, the outside of the tube on the bottom can have a two layer coating applied to it. A code can then be etched into the top or outermost layer of the coating by a laser etching process or the like. Such technology has been used by Matrix.
This process has a number of inherent disadvantages. Firstly, the etchable coating must be applied to the bottom of the tube. These tubes are typically used with a wide range of organic solvents including DMSO. It follows that, in the event of a spillage, the two layer coating must be both secure and completely inert to all solvents. This is not easy to achieve and, where it has been achieved, inevitably increases the cost significantly.
Secondly, if the top coating becomes scratched slightly during manipulation of the tube, then this could alter or degrade the unique code by accident. This could have very serious implications for an experiment and many man hours and expensive reagents could be lost in repeat experiments. Where the original sample was unique, it could be that the experiment can never be repeated.
All of the above adds to the cost of the finished product.
In a further known example of coding a tube, a slug of non-transparent rubber or plastics material is embedded into the base of the tube. This is then coded by laser etching directly, usually with a series of pits in the form of a binary code. Once again, if a spurious scratch or pit finds its way onto the bottom of the tube the unique code is lost. In addition, the process for embedding or attaching a slug or layer of opaque material on the bottom of a small tube is not necessarily straightforward and adds significantly to the cost of the tube even before adding the cost of laser etching.
It is also known to attach an electronic code carrier to the base of a tube. Examples of this type of technology are described in WO89/08264 (Ballies) and WO99/03585 (Clids OY). In both these examples the memory device is detachable. Although the memory device is encapsulated in a liquid-tight casing this is not sealed to the bottom of the tube.
Collectively, this is the closed prior art know to the applicant.
It is the object of the present invention to eliminate or at least mitigate some or all of the problems outlined above.